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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. GRB 181225A: CALET Gamma-Ray Burst Monitor detection
  2. GRB 181225A: KAIT Follow-Up Observations with Upper Limit
  3. GRB 181228A: KAIT Optical Upper Limit
  4. GRB 181228A: Swift detection of a burst
  5. GRB 181227A: Fermi GBM detection
  6. GRB 181222B: Swift ToO observations
  7. GRB 181225A: Insight-HXMT/HE detection
  8. GRB 181222A: AstroSat CZTI detection
  9. GRB 181225A: Swift observations and X-ray candidate afterglow
  10. GRB 181225A: Global MASTER Net optical observations
  11. GRB 181225A: Swift ToO observations
  12. GRB 181225A: Fermi GBM detection
  13. GRB 181225A: Fermi-LAT Detection
  14. GRB 181225A: AGILE/MCAL detection of a burst
  15. Konus-Wind observation of GRB 181222A
  16. GRB 181222B: Global MASTER Net observations of short bright Fermi GRB
  17. Konus-Wind observation of GRB 181222B
  18. IPN Triangulation of extremely bright short GRB 181222B
  19. GRB 181224A: Swift-BAT refined analysis
  20. GRB 181224A: Swift detection of a burst
  21. GRB 181222A: CALET Gamma-Ray Burst Monitor detection
  22. GRB 181222B: Global MASTER Net observations of the short bright Fermi GRB error box.
  23. GRB 181222B : Fermi GBM detection
  24. Trigger 878548: Swift detection of AX 1631.9-4752
  25. Swift Trigger 878504 is not astrophysical
  26. GRB 181222A: Fermi GBM observation
  27. GRB 181222A: MAXI/GSC detection
  28. GRB 181217A: Insight-HXMT/HE detection
  29. GRB 181213A: Swift/UVOT Observations
  30. GRB 181213A: Mondy optical observations
  31. GRB 181213A: continued TSHAO optical observations
  32. GRB 181213A:Insight-HXMT/HE detection
  33. GRB 181212A:Insight-HXMT/HE detection
  34. Konus-Wind observation of GRB 181212A
  35. GRB 181213A: AbAO optical observations
  36. GRB 181213A: HMM-0.5m, NEXT-0.6m, CNEOST-1m optical observations
  37. GRB 181213A: NOT optical observations
  38. GRB 181213A: Swift-XRT refined Analysis
  39. GRB 181213A: Enhanced Swift-XRT position
  40. IPN Triangulation of GRB 181212A (long)
  41. GRB 181213A: Swift-BAT refined analysis
  42. GRB 181213A: GWAC-F60A upper limit
  43. GRB 181126A: MeerKAT radio observation
  44. GRB 181213A : TSHAO optical observations
  45. GRB181213A: Swift/UVOT Detection
  46. GRB 181213A: Swift-XRT observations
  47. GRB 181213A: BOOTES-5/JGT optical observations
  48. SWIFT GRB181213A Global MASTER-Net bright OT discovery
  49. GRB 181213A: Swift detection of a burst
  50. GRB 181212A: Fermi GBM Detection
  51. GRB 181126B: KAIT Follow-Up Observations of a Fermi Short GRB (Trigger 564897175)
  52. GRB 181201A: continued optical observations in Mondy
  53. MASTER OT J063515.49-624002.9 of Fermi trigger 565936249: optical observations in SAAO
  54. MASTER: OTs detection during Fermi alert trigger 565936249 early observations
  55. GRB 181201A: VLA detection
  56. GRB 181201A: ALMA detection of a fading mm afterglow
  57. INTEGRAL observations of the events in the GWTC-1 catalog
  58. GRB 181203A: GROND detection of the afterglow
  59. GRB 181126B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 564897175)
  60. GRB 181201A: continued optical observations in TSHAO and Chilesope
  61. GRB 181203A: BOOTES-3/YA optical observations
  62. GRB 181205A: a long GRB detected by INTEGRAL
  63. GRB 180112B: AstroSat CZTI detection
  64. GRB181201A: Optical afterglow measurements by GROWTH-India
  65. Swift Trigger 874754 is likely not an astrophysical event
  66. Fermi-GBM Observations During Four New GW-Detected BBH Mergers (Correction)
  67. GRB 181201A: continued optical observations in TSHAO
  68. Fermi-GBM Observations During Four New GW-Detected BBH Mergers
  69. GRB 181203A: Swift/UVOT Upper Limits
  70. GRB 181201A: Continued GROND observations show that afterglow is still bright
  71. GRB181201A: GOTO optical observations
  72. GRB 181203A: Swift-XRT refined Analysis
  73. GRB 181201A: AstroSat CZTI detection
  74. GRB 181203A: Swift-BAT refined analysis
  75. GRB 181201A: Swift/UVOT Detection
  76. GRB 181202A: Swift/UVOT Detection
  77. GRB 181201A: continued optical observations in SAAO and Chilesope
  78. GRB 181202A: RATIR Optical and NIR Observations
  79. Konus-Wind observation of GRB 181201A
  80. GRB 181203A: Enhanced Swift-XRT position
  81. GRB 181203A: Swift detection of a burst
  82. GRB 181201A: Further COATLI Optical Monitoring
  83. GRB 181201A: Insight-HXMT/HE detection
  84. GRB 181202A: Global MASTER-Net optical observations
  85. GRB 181202A: Swift-BAT refined analysis
  86. GRB 181201A: VLT/FORS2 tentative spectroscopic redshift
  87. GRB 181202A: Swift-XRT refined Analysis
  88. GRB 181201A: GROND detection of the afterglow and redshift upper limit of z < 3
  89. GRB 181201A: optical observations in Chilescope observatory
  90. GRB 181201A: Global MASTER-Net prompt optical descovery and afterglow observations
  91. GRB 181202A: Enhanced Swift-XRT position
  92. GRB 181202A: Swift detection of a burst with an optical counterpart
  93. GRB 181201A: COATLI Optical Detection
  94. GRB 181201A: Fermi-LAT detection
  95. GRB 181201A: Zeiss-1000/CrAO optical observations
  96. GRB 181201A: NOT optical observations
  97. GRB 181201A: optical observations in SAAO
  98. GRB 181201A MASTER-Net OT continued observation
  99. GRB 181201A: iTelescope optical afterglow detection
  100. GRB 181201A: Swift-XRT afterglow detection

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